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Biomedical subjects

M Yamauchi

Publications and source records attributed to M Yamauchi.

At least 19 recordsLinked to original sources
PubMed2007

Removal of noncollagenous components affects dentin bonding.

The structural integrity of fibrillar type I collagen is critical for effective dentin bonding. Since most noncollagenous matrix components in dentin are closely associated with collagen, we hypothesized that they may also contribute to dentin bonding. To test this hypothesis, bovine dentin was acid-etched, treated with chondroitinase ABC (C-ABC), endo-beta-galactosidase (Endo-beta), or trypsin. Controls were prepared in the same manner but without the enzymes. All control and experimental specimens were then bonded with One-Step. Bond strength data were analyzed by one-way ANOVA and Fisher's PLSD test (p < 0.05). When dentin was treated with C-ABC or trypsin, bond strengths significantly decreased for the rewetted groups (p < 0.05). The treatment with Endo-beta showed no effects on bond strengths (p > 0.05). When the treated dentin surfaces were observed under SEM, the C-ABC and trypsin treated groups revealed significant loss of collagen fibril architecture. The results indicate that chondroitin sulfate glycosaminoglycans and trypsin-digestible noncollagenous proteins play roles in maintaining the open dimensions of the collagen fibril scaffold, which is essential for optimal dentin bonding.

Acid Etching, Dental↗
PubMed2006

Protective effect against 17beta-estradiol on neuronal apoptosis in hippocampus tissue following transient ischemia/recirculation in mongolian gerbils via down-regulation of tissue transglutaminase activity.

We analyzed the protective effect of 17beta-estradiol (17beta-ED) injection against delayed neuronal death in the hippocampus tissue of the brain in Mongolian gerbils after transient ischemia/recirculation treatment, especially in relation with bcl-2 gene expression and enzymatic activity changes of caspase-3 and tissue transglutaminase (tTGase). Daily intraperitoneal injection of 17beta-ED to the animal after the ischemia stimulated the expression of an apoptosis suppressor gene, bcl-2, in the hippocampal tissue for a week. The gradually increasing apoptotic enzyme activity of caspase-3 and increased number of TUNEL positive fragmented neuronal nuclei caused by ischemic attack in the gerbil brain were clearly suppressed by 17beta-ED administration. The reduced activity and enzyme protein of tTGase, a neurodegenerative marker of apoptosis in the hippocampus after ischemia, were also restored to nearly normal levels by 17beta-ED injection. These results suggest that daily 17beta-ED administration to the gerbil after transient ischemic insult with progressing neuronal deteriorative changes in hippocampus tissue can effectively prevent apoptotic changes through a molecular cascade involving gene expression regulation.

Animals↗
PubMed2006

Serum levels of insulin-like growth factor (IGF); IGF-binding proteins-3, -4, and -5; and their relationships to bone mineral density and the risk of vertebral fractures in postmenopausal women.

We previously found that serum levels of insulin-like growth factor I (IGF-I) and IGF-binding protein (IGFBP)-3, but not IFGBP-2, were associated with bone mineral density (BMD) and the risk of vertebral fractures. The aim of the present study was to investigate the roles of IGFBP-4 and -5 in age-dependent bone loss and vertebral fracture risk in postmenopausal Japanese women and to compare them with those of IGF-I and IGFBP-3. One hundred and ninety-three Japanese women aged 46-88 years (mean 62.5) were enrolled in the cross-sectional study. BMD was measured at the lumbar spine, femoral neck, ultradistal radius (UDR), and total body by dual-energy X-ray absorptiometry. Serum levels of IGFBP-4 and -5 as well as IGF-I and IGFBP-3 were measured by radioimmunoassay. Serum levels of IGF-I, IGFBP-3, and IGFBP-5 declined with age, while serum IGFBP-4 increased with age. Multiple regression analysis was performed between BMD at each skeletal site and serum levels of IGF-I and IGFBPs adjusted for age, body weight, height, and serum creatinine. BMD at the UDR was significantly and positively correlated with all serum levels of IGF-I and IGFBPs measured (P < 0.01), while BMD at the femoral neck was correlated with none of them. Serum IGF-I level was significantly and positively correlated with BMD at all sites except the femoral neck (P < 0.01), while serum IGFBP-3 and -4 levels were significantly and positively correlated with only radial BMD (P < 0.01). Serum IGFBP-5 level was positively correlated with UDR BMD (P < 0.001) and negatively correlated with total BMD (P < 0.05). Serum IGF-I, IGFBP-3, and IFGBP-5 levels were significantly lower in women with vertebral fractures than in those without fractures (mean +/- SD: 97.1 +/- 32.1 vs. 143.9 +/- 40.9 ng/dl, P < 0.0001; 2.18 +/- 1.02 vs. 3.23 +/- 1.07 microg/ml, P < 0.0001; 223.6 +/- 63.3 vs. 246.5 +/- 71.5 ng/ml, P = 0.0330, respectively). When multivariate logistic regression analysis was performed with the presence of vertebral fractures as a dependent variable and serum levels of IGF-I and IGFBPs adjusted for age, body weight, height, serum creatinine, and serum alubumin as independent variables, IGF-I and IGFBP-3 were selected as indices affecting the presence of vertebral fractures [odds ratio (OR) = 0.29, 95% confidential interval (CI) 0.15-0.57 per SD increase, P = 0.0003 and OR = 0.31, 95% CI 0.16-0.61 per SD increase, P = 0.0007, respectively]. To compare the significance values, IGF-I, IGFBP-3, and age were simultaneously added as independent variables in the analysis. IGFBP-3 was more strongly associated with the presence of vertebral fractures than IGF-I and age (P = 0.0006, P = 0.0148, and P = 0.0013, respectively). Thus, after comprehensive measurements of serum levels of IGF-I and IGFBPs, it seems that serum IGF-I level is most efficiently associated with bone mass and that serum IGFBP-3 level is most strongly associated with the presence of vertebral fractures in postmenopausal women among the IGF system components examined.

Aged↗
PubMed2006

The usefulness of bone metabolic indices for the prediction of changes in bone mineral density after parathyroidectomy in patients with primary hyperparathyroidism.

Patients with primary hyperparathyroidism (pHPT) have reduced bone mineral density (BMD). Although pHPT causes high bone turnover, the exact metabolic bone markers useful for predicting changes in BMD after parathyroidectomy (PTX) remain elusive. The present study was performed to examine the relationship between bone metabolic indices and BMD changes after PTX in 29 pHPT Japanese patients, which received PTX successfully. BMD values were measured by dual-energy X-ray absorptiometry in the lumbar spine and distal one third of radius. As for bone metabolic indices, serum bone-type alkaline phosphates (BAP), serum osteocalcin (OCN), urinary deoxypiridinoline (Dpd), and urinary type I collagen cross-linked N-telopeptides (NTX) were measured. The study included 10 male and 19 female patients (17 postmenopausal). Urinary Dpd, but not NTX was significantly correlated with serum BAP and OCN. Either bone formation or bone resorption indices were significantly and highly correlated with Z-score of BMD in the radius, but not at lumbar spine. Urinary Dpd was significantly correlated with BMD changes at both lumbar spine and radius and at all time points over the two years after PTX. These correlations were most potent among bone metabolic indices in this study. The measurement of urinary Dpd would be useful for predicting long-term changes in BMD at radial and lumbar spine after PTX than other bone metabolic indices.

Bone Density↗
PubMed2006

On-site treatment of high-strength alcohol distillery wastewater by a pilot-scale thermophilic multi-staged UASB (MS-UASB) reactor.

A pilot-scale multi-staged UASB (MS-UASB) reactor with a working volume of 2.5 m3 was operated for thermophilic (55 degrees C) treatment of an alcohol distillery wastewater for a period of over 600 days. The reactor steadily achieved a super-high rate COD removal, that is, 60 kgCOD m(-3) d(-1) with over 80% COD removal. However, when higher organic loading rates were further imposed upon the reactor, that is, above 90 kgCOD m(-3) d(-1) for barely-based alcohol distillery wastewater (ADWW) and above 100 kgCOD m(-3) d(-1) for sweet potato-based ADWW, the reactor performance somewhat deteriorated to 60 and 70% COD removal, respectively. Methanogenic activity (MA) of the retained sludge in the thermophilic MS-UASB reactor was assessed along the time course of continuous run by serum-vial test using different substrates as a vial sole substrate. With the elapsed time of continuous run, hydrogen-utilizing MA, acetate-utilizing MA and propionate-fed MA increased at maximum of 13.2, 1.95 and 0.263 kgCOD kgVSS(-1) d(-1), respectively, indicating that propionate-fed MA attained only 1/50 of hydrogen-utilizing MA and 1/7 of acetate-utilizing MA. Since the ADWW applied herewith is a typical seasonal campaign wastewater, the influence of shut-down upon the decline in sludge MA was also investigated. Hydrogen-utilizing MA and acetate-utilizing MA decreased slightly by 3/4, during a month of non-feeding period, whereas propionate-fed MA were decreased significantly by 1/5. Relatively low values of propionate-fed MA and its vulnerability to adverse conditions suggests that the propionate degradation step is the most critical bottleneck of overall anaerobic degradation of organic matters under thermophilic condition.

Alcohols↗
PubMed2005

Body composition and vertebral fracture risk in female patients treated with glucocorticoid.

INTRODUCTION: Glucocorticoid (GC) causes bone loss and an increase in bone fragility. However, fracture risk was found to be only partly explained by bone mineral density in GC-treated patients (GC patients). Although GC causes a change in the distribution of fat in the body, the relationship between body composition and fracture risk in GC patients remains unknown. METHODS: The present study examined the relationship between the presence or absence of vertebral fractures and various indices, including body composition, in 92 premenopausal GC patients, 122 postmenopausal GC patients and 122 postmenopausal age-matched control subjects. Dual-energy X-ray absorptiometry was employed to analyze body composition. RESULTS: Percentage lean body mass (LBM), % fat and % trunk fat were not significantly different between postmenopausal GC patients and the control women. When groups with and without vertebral fractures were compared, % LBM and % fat were significantly higher and lower in groups with vertebral fractures, respectively, in postmenopausal GC patients, but not in the postmenopausal control women, although % trunk fat was not significantly different between groups with and without vertebral fractures. Femoral neck BMD was negatively correlated with % LBM and positively correlated with % fat. In premenopausal GC patients, % trunk fat was significantly higher in the fracture group, although % LBM and % fat were not significantly different between groups with and without vertebral fractures. CONCLUSION: The present study revealed that body composition is related to vertebral fracture risk in GC-treated patients. Lower % fat can be included in the determination of vertebral fractures in postmenopausal GC-treated patients. The influence of body composition on vertebral fracture risk may be different between the pre- and postmenopausal state in GC patients.

Absorptiometry, Photon↗
PubMed2005

Discovery of the short gamma-ray burst GRB 050709.

Gamma-ray bursts (GRBs) fall into two classes: short-hard and long-soft bursts. The latter are now known to have X-ray and optical afterglows, to occur at cosmological distances in star-forming galaxies, and to be associated with the explosion of massive stars. In contrast, the distance scale, the energy scale and the progenitors of the short bursts have remained a mystery. Here we report the discovery of a short-hard burst whose accurate localization has led to follow-up observations that have identified the X-ray afterglow and (for the first time) the optical afterglow of a short-hard burst; this in turn led to the identification of the host galaxy of the burst as a late-type galaxy at z = 0.16 (ref. 10). These results show that at least some short-hard bursts occur at cosmological distances in the outskirts of galaxies, and are likely to be caused by the merging of compact binaries.

Journal Article↗
PubMed2005

Tissue- and bone cell-specific expression of bone sialoprotein is directed by a 9.0 kb promoter in transgenic mice.

Bone sialoprotein (BSP) is a phosphorylated glycoprotein that is expressed almost exclusively in mineralizing connective tissues. In bone, expression of BSP correlates with the differentiation of osteoblasts and the onset of mineralization. To determine how the tissue- and differentiation-specific transcription of BSP is regulated, various lengths of promoter sequence were ligated to a luciferase reporter and stably transfected into a rat stromal bone marrow cell line, RBMC-D8 and undifferentiated C3H10T1/2 cells. Luciferase transcription of reporter constructs including 5.4 kb (mBSP5.4Luc) and 9.0 kb (mBSP9.0Luc) of the BSP promoter was strongly up-regulated in parallel with endogenous BSP mRNA in differentiating SBMCs, but not in C3H10T1/2 cells. In contrast, 0.1 kb and 1.4 kb BSP promoter constructs did not show selective expression. To determine tissue-specific expression in vivo, transgenic mice expressing reporter constructs for the 9.0 kb promoter and a 4.8 kb promoter lacking two upstream Cbfa1/Runx2 elements (mBSP9.0Luc and mBSP4.8Luc, respectively) were generated. Analysis of various tissues collected from 1-, 4-, 7-, 14-, and 42-day-old mice revealed extremely high levels of luciferase activity in calvaria, mandible, and tibia of the mBSP9.0Luc mice. In contrast, soft tissues showed negligible luciferase expression. Mice harboring the 4.8 kb transgene also showed selective luciferase expression but displayed a significantly lower activity in mineralized tissues. Northern hybridization of endogenous BSP mRNA and immunostaining of BSP in mBSP9.0Luc mice showed a temporo-spatial expression pattern consistent with the luciferase activity. These results indicate that regulatory elements within the 9.0 kb region of the promoter are required for strong, tissue- and differentiation-specific expression of BSP.

Animals↗
PubMed2005

Shielding design of the ITER NBI duct for nuclear and bremsstrahlung radiation.

Three-dimensional Monte Carlo shielding analyses are conducted on the ITER Neutral Beam Injection (NBI) duct for the nuclear and bremsstrahlung radiation. The detailed distribution is evaluated about the nuclear heating rate and surface heat load of the NBI duct wall by the neutron and photon transport calculation. The analytical representations of these nuclear responses are established as a function of the distance from the blanket surface. It is clarified that these representations are different between the duct wall facing the plasma and that hidden from the plasma, and also between the duct wall in the blanket region and that in the vacuum vessel region. These results are very useful for the shielding design of the NBI duct wall in the nuclear fusion reactor.

Computer Simulation↗
PubMed2005

Experiment and analyses for 14 MeV neutron streaming through a dogleg duct.

There are several vacant channels for diagnosis, RF heating and so on through the shielding structure in fusion reactors. Some of them consist of dogleg ducts, through which neutrons stream in a complex manner. An experiment was conducted with the Fusion Neutronics Source (FNS) facility at JAERI to study the behaviour of neutrons in the duct and assess the reliability of calculation methods for the design of fusion reactors such as ITER. The assembly was an iron slab 180 cm in thickness with a doubly bent duct 30 x 30 cm2 in cross section. The experiment was analysed using a simple design code for radiation streaming, DUCT-III, and the Monte Carlo code MCNP. The results indicate that the simple design code is reliable enough to be used for shielding design analyses as well as the Monte Carlo method, which showed excellent agreement between calculated and measured values.

Algorithms↗
PubMed2005

A stylized computational model of the head for the reference Japanese male.

Computational models of human anatomy, along with Monte Carlo radiation transport simulations, have been used by Snyder et al. [MIRD Pamphlet No. 5, revised (The Society of Nuclear Medicine, New York, 1978)], Cristy and Eckerman [ORNL/TM-8381/VI, Oak Ridge National Laboratory, Oak Ridge, TN (1987)] and Zubal et al. [Med. Phys. 21, 299-302 (1994)] to estimate internal organ doses from internal and external radiation sources. These were created using physiological data from Caucasoid subjects but not from other races. There is a need for research to determine whether the obvious differences from the Caucasoid anatomy make these models unsuitable for estimating the absorbed dose in other races such as the Mongoloid. We used the cranial region of the adult Japanese male to represent the Mongoloid race. This region contains organs that are highly sensitive to radiation. The cranial region of a physical phantom produced by KYOTO KAGAKU Co., LTD. using numerical data from a Japanese Reference Man [Tanaka, Nippon Acta. Radiol. 48, 509-513 (1988)] was used to supply the data for the geometry of a stylized computational model. Our computational model was constructed with equations rather than voxel-based, in order to deal with as small a number of parameters as possible in the computer simulation experiment. The accuracy of our computational model was checked by comparing simulated experimental results obtained with MCNP4C with actual doses measured with thermoluminescence dosimeters (TLDs) inside the physical phantom from which our computational model was constructed. The TLDs, whose margin of error is less than +/-10%, were arranged at six positions. Co-60 was used as the radiation source. The irradiated dose was 2 Gy in terms of air kerma. In the computer simulation experiments, we used our computational model and Cristy's computational model, whose component data are those of the tissue substitute materials and of the human body as published in ICRU Report 46. The observed absorbed dose values (Gy) at all six points were calculated as the percentage difference between MCNP4C simulation and the TLDs. In our computational model, the average values of all the percentage differences were 6.0+/-4.0% (tissue substitute materials) and 7.6+/-6.6% (ICRU Report 46), respectively. In Cristy's model, the corresponding values were 20.4+/-3.8% (tissue substitute materials) and 21.0+/-4.1% (ICRU Report 46), respectively. Considering the margin of error in the radiation sensitivity of the TLDs, this study validates our computational model as a test object for radiation dosimetry studies.

Asian People↗
PubMed2004

Heterogeneous basis of the type VIB form of Ehlers-Danlos syndrome (EDS VIB) that is unrelated to decreased collagen lysyl hydroxylation.

Skin fibroblasts from the majority of patients with the clinical diagnosis of Ehlers-Danlos syndrome type VI (EDS VI; kyphoscoliosis type), have significantly decreased lysyl hydroxylase (LH) activity due to mutations in the LH1 gene (classified as EDS VIA: OMIM no. 225400). A rare condition exists in which patients are clinically similar but have normal levels of LH activity (designated EDS VIB: OMIM no. 229200). To define the biochemical defect, we have examined cultured fibroblasts from four EDS VIB patients for changes in the levels of the mRNAs for LH1, LH2, and LH3, collagen cross-linking patterns, and the extent of lysine hydroxylation of type I collagen alpha chains. Although normal levels of LH1 mRNA were observed in all four patients, in two patients the levels of LH2 mRNA were decreased by >50%, and a similar decrease was observed in LH3 mRNA in the other two patients. A distinct pattern of collagen cross-links, indicative of decreased lysyl hydroxylation, could be identified in EDS VIA patients, but there was no clear correlation between collagen cross-link pattern and changes in the individual LH mRNAs in EDS VIB patients. Linkage to tenascin-X was excluded in these patients. This study suggests that the basis for this form of EDS VI is genetically heterogeneous, and that alternative pathways in addition to lysine hydroxylation of collagen may be affected.

Cell Line↗
PubMed2004

Solar wind-induced atmospheric erosion at Mars: first results from ASPERA-3 on Mars Express.

The Analyzer of Space Plasma and Energetic Atoms (ASPERA) on board the Mars Express spacecraft found that solar wind plasma and accelerated ionospheric ions may be observed all the way down to the Mars Express pericenter of 270 kilometers above the dayside planetary surface. This is very deep in the ionosphere, implying direct exposure of the martian topside atmosphere to solar wind plasma forcing. The low-altitude penetration of solar wind plasma and the energization of ionospheric plasma may be due to solar wind irregularities or perturbations, to magnetic anomalies at Mars, or both.

Journal Article↗
PubMed2004

Partial biochemical characterisation of collagen in carious dentin of human primary teeth.

The process of dentin caries is a complex event involving demineralisation and matrix degradation. The objective of this study was to biochemically characterise collagen, the major dentin matrix component, by amino acid and cross-link analyses in two distinct carious dentin regions of human primary teeth. Twenty-seven carious primary teeth were obtained from 3 to 11-year-old patients and three layers of dentin, i.e. outer, inner carious dentin and normal dentin, were identified by a 1% acid red solution and dissected from each tooth. The samples were pulverised, the respective layers obtained from three to five teeth were pooled and six samples per layer were analysed. Aliquots of the dried dentin powder were hydrolysed with 6N HCl at 110 degrees C for 24h and subjected to amino acid analyses. Other aliquots were demineralised, reduced with standardised NaB3H4, hydrolysed and subjected to quantitative collagen cross-link analyses. The results demonstrated that in the outer carious layer the collagen-associated amino acids were significantly lower and the reducible cross-links were markedly diminished when compared to the other two groups. There was no significant difference in these parameters between the inner carious and the normal layers. The data indicate that while the collagen in the outer carious dentin is significantly altered and degraded, the one in the inner carious dentin is relatively unaffected in primary teeth.

Amino Acids↗
PubMed2004

Decreased expression of lysyl hydroxylase 2 (LH2) in skin fibroblasts from three Ehlers-Danlos patients does not result from mutations in either the coding or proximal promoter region of the LH2 gene.

The Ehlers-Danlos syndromes (EDS) are a heterogeneous group of inherited connective tissue disorders characterized by tissue fragility, hyperelasticity of the skin and joint hypermobility. This phenotype, accompanied by kyphoscoliosis and/or ocular fragility, is present in patients with the autosomal recessive type VI form of EDS. These patients have significantly decreased levels of lysyl hydroxylase (LH) activity, due to mutations in the LH1 gene. LH hydroxylates specific lysine residues in the collagen molecule that are precursors for the formation of cross-links which provide collagen with its tensile strength. No disorder has been directly linked to decreased expression of LH2 and LH3, two other isoforms of LH. This study describes 3 patients with mixed phenotypes of EDS, who have significantly decreased mRNAs for LH2, but normal levels of LH1 and LH3 mRNAs, in their skin fibroblasts. In contrast to the effect of LH1 deficiency in EDS VI patients, the decreased expression of LH2 does not affect LH activity, bifunctional collagen cross-links (measured after reduction as dihydroxylysinonorleucine (DHLNL) and hydroxylysinonorleucine (HLNL)), or helical lysine hydroxylation in these cell lines. Sequence analysis of full length LH2 cDNAs and 1kb of the promoter region of LH2 does not show mutations that could explain the decreased expression of LH2. These results suggest that the deficiency of LH2 in these fibroblasts may be caused by changes in other factors required for the expression of LH2.

Cell Line↗
PubMed2004

GAFChromic film dosimetry with a flatbed color scanner for Leksell Gamma Knife therapy.

GAFChromic films MD-55-2 have recently been established widely in industrial, scientific, and medical applications as radiation dosimeters. We applied these films to the dosimetry for Leksell Gamma Knife therapy. We used a flatbed image scanner to take digital images of irradiated MD-55-2, and the data were converted to Red, Green and Blue pixel values. The absorbed dose, as derived from the response curve of the Red pixel value, was consistent with the Leksell Gamma Plan dose planning system, for exposures using collimator sizes, 4 mm, 8 mm, and 14 mm. However, the maximum dose in the exposure of the 18 mm collimator was measured to be about 5% smaller than Gamma Plan due to the density effect of the compound material in the head phantom.

Algorithms↗
PubMed2004

Collagen cross-linking and ultimate tensile strength in dentin.

Several studies have indicated differences in bond strength of dental materials to crown and root dentin. To investigate the potential differences in matrix properties between these locations, we analyzed upper root and crown dentin in human third molars for ultimate tensile strength and collagen biochemistry. In both locations, tensile strength tested perpendicular to the direction of dentinal tubules (undemineralized crown = 140.4 +/- 48.6/root = 95.9 +/- 26.1; demineralized crown = 16.6 +/- 6.3/root = 29.0 +/- 12.4) was greater than that tested parallel to the tubular direction (undemineralized crown = 73.1 +/- 21.2/root = 63.2 +/- 22.6; demineralized crown = 9.0 +/- 3.9/root = 16.2 +/- 8.0). The demineralized specimens showed significantly greater tensile strength in root than in crown. Although the collagen content was comparable in both locations, two major collagen cross-links, dehydrodihydroxylysinonorleucine/its ketoamine and pyridinoline, were significantly higher in the root (by ~ 30 and ~ 55%, respectively) when compared with those in the crown. These results indicate that the profile of collagen cross-linking varies as a function of anatomical location in dentin and that the difference may partly explain the site-specific tensile strength.

Adolescent↗